Echidna - info and games Echidna Echidnas, sometimes also referred to as "spiny anteaters", are the only surviving monotremes apart from the Platypus. The four surviving species, native to New Guinea and Australia, all belong to the Tachyglossidae family. The echidna is named after a monster in ancient Greek mythology. Big Nose/Mouth: Echidnas are small mammals that are covered with coarse hair and spines. Superficially they resemble both the anteaters of South America and other spiny mammals like hedgehogs and porcupines. They have snouts which have the functions of both the mouth and nose. Their snouts are elongated and slender. They have very short, strong limbs with large claws and are powerful diggers. What's For Dinner? Echidnas have a tiny mouth and a toothless jaw. They feed by tearing open soft logs, anthills and the like, and using their long, sticky tongue which protrudes from their snout to collect their prey. The Short-beaked echidna's diet consists largely of ants and termites, while the Zaglossus species typically eat worms and insect larvae.

Short-beak: The Short-beaked echidna (Tachyglossus aculeatus), also known as the Spiny anteater because of its diet of ants and termites, is one of four living species of echidna and the only member of the genus Tachyglossus. The Short-beaked echidna is covered in fur and spines and has a distinctive snout and a specialized tongue, which it uses to catch its prey at a great speed. Like the other extant monotremes, the Short-beaked echidna lays eggs; the monotremes are the only group of mammals to do so. Echidna in Trouble: The species is found throughout Australia, where it is the most widespread native mammal, and in coastal and highland regions of southwestern New Guinea, where it is known as the Mungwe in the Daribi and Chimbu languages. It is not threatened with extinction, but human activities, such as hunting, habitat destruction, and the introduction of foreign predatory species and parasites, have reduced the distribution of the Short-beaked echidna in Australia.

Vagabonds of the Outback: No systematic study of the ecology of the Short-beak echidna has been published; however, there have been studies of several aspects of their ecological behavior. Short-beaked echidnas live alone and apart from the burrow created for rearing young; they have no fixed shelter or nest site. They do not have a home territory, but range over a wide area. Morning People... sort of: Short-beaked echidnas are typically active in the daytime; however, they are ill-equipped to deal with heat, because they have no sweat glands and do not pant. Therefore, in warm weather they change their pattern of activity, becoming crepuscular or nocturnal. They can tolerate cold temperatures, and hibernate during the winter in very cold regions. They Follow the Food! Short-beaked echidnas can live anywhere that has a good supply of food. Short-beaked echidnas locate food by smell, using sensors in the tip of their snout, and regularly feast on ants and termites. They are powerful diggers, using their clawed front paws to dig out prey and create burrows for shelter. They may rapidly dig themselves into the ground if they cannot find cover when in danger.

Where the Echidnas Roam: In Australia they are most common in forested areas where there are abundant termite-filled fallen logs. In agricultural areas, they are most likely to be found in uncleared scrub; they may be found in grassland, arid areas, and in the outer suburbs of the capital cities. Little is known about their distribution in New Guinea, they have been found in southern New Guinea between Merauke in the west, to the Kelp Welsh River, east of Port Moresby in the east, where they may be found in open woodland. Egg-layers! Apart from the Platypus, the four species of echidna are the only egg-laying mammals. The female lays a single soft-shelled, leathery egg twenty-two days after mating and deposits it directly into her pouch. Hatching takes ten days; the young echidna, called a puggle, then sucks milk from the pores of the two milk patches (monotremes have no nipples) and remains in the pouch for forty-five to fifty-five days, at which time it starts to develop spines.

The mother digs a nursery burrow and deposits the puggle, returning every five days to suckle it until it is weaned at seven months. The Smell of Romance: The solitary Short-beaked echidna looks for a mate between May and September; the precise timing of the mating season varies with geographic location. Both males and females give off a strong odor during the mating season. During courtship, males locate and pursue females. Trains of up to ten males may follow a single female in a courtship ritual that may last for up to four weeks; the duration of the courtship period varies with location. In cooler parts of their range, such as Tasmania, females may mate within a few hours of arousal from hibernation. Before mating, the male smells the female, paying particular attention to the cloaca. The male is often observed to roll the female onto her side and then assumes a similar position so that the two animals are abdomen to abdomen. #1 Egg: Each mating results in the production of a single egg, and females are known to mate only once during the breeding season; each mating is successful. Fertilization occurs in the oviduct.

Gestation takes between 21 and 28 days, during which time the female constructs a nursery burrow. Following the gestation period, a single rubbery-skinned egg between 13 and 17 millimeter in diameter is laid directly into a small, backward-facing pouch that has developed on her abdomen. Ten days after it is laid, the egg hatches within the pouch. The embryo develops an "egg tooth" during incubation, which it uses to tear open the egg; the tooth disappears soon after hatching. Hatchlings are about 1.5 cm long and weigh between 0.3 and 0.4 grams. After hatching, young echidnas are known as puggles. Mother's Milk: Hatchlings attach themselves to their mothers' milk areolae, a specialized patch on the skin that secretes milk (monotremes lack nipples). The way in which puggles imbibe the milk is not yet known, but they have been observed ingesting large amounts during each feeding period, since mothers may leave them unattended in the burrow for between five and ten days.

The principal components of the milk are fucosyllactose and saialyllactose; it is high in iron content, giving it a pink color. Ejected from the Pouch: Juveniles are eventually ejected from the pouch at around two to three months of age, because of the continuing growth in the length of their spines. Suckling gradually decreases until juveniles are weaned at about six months of age. The duration of lactation is about 200 days, and the young leave the burrow between 180 and 240 days. The age of sexual maturity is uncertain, but may be four to five years. A twelve-year field study, published in 2003, found that the Short-beaked Echidna reached sexual maturity between five and 12 years of age, and that the frequency of reproduction varies from once every two years to once every six years. The Short-beaked Echidna can live as long as 45 years in the wild. Echidnas are classified into two genera. The Zaglossus genus includes three surviving species and two extinct species known only from fossils; while only one species of the Tachyglossus genus is known.

The three living Zaglossus species are endemic to New Guinea. They are rare, and hunted for food. They forage in leaf litter on the forest floor, eating earthworms and insects. * The Western Long-beaked Echidna (Zaglossus bruijni) of the highland forests. * Sir David's Long-beaked Echidna (Zaglossus attenboroughi), recently discovered, and prefers a still higher habitat. * The Eastern Long-beaked Echidna (Zaglossus bartoni), of which 4 distinct subspecies have been identified The Tachyglossus genus consists only of the Short-beaked Echidna (Tachyglossus aculeatus) is found in south east New Guinea and also occurs in almost all Australian environments: from the snow-clad Australian Alps to the deep deserts of the Outback: essentially anywhere that ants and termites are available. Its size is smaller than the Zaglossus species and it has longer hair. All text is available under the terms of the GNU Free Documentation License Platypus Genome - Science Updates - Science NetLinks Science NetLinks Scientists have sequenced the genetic code of one of nature's strangest animals.

Transcript Piecing together the platypus puzzle. I'm Bob Hirshon and this is Science Update. The duck-billed platypus looks like it's been stitched together from spare parts, which has baffled scientists for centuries. Now, they've finally cracked its genetic code, which could help them understand other mammals too. Geneticist Wes Warren of the Washington University School of Medicine explains that the platypus is one of only five surviving species of ancient egg-laying mammals called monotremes. They were the first mammals to branch off from their reptile-like ancestors. Warren: And we really needed to fill that hole in our phylogenetic tree to better understand the emergence of mammal-specific traits. Those include lactation, sweat glands, and a sophisticated brain area called the neocortex. By studying primitive versions of those genes in the platypus, researchers hope to uncover new insights into gene function in all mammals. I'm Bob Hirshon for AAAS, the science society. Making Sense of the Research Even though it lives only in Australia, most people learn about the platypus from an early age, because it's such a funny-looking animal.

It also makes a good trivia question, since it's a mammal with a bill like a duck that lays eggs. Like all mammals, though, the platypus has hair and sweat glands, is “warm-blooded” (in other words, it regulates its body temperature internally), and produces milk to feed its young. It also has two lesser-known but key mammalian traits: a single lower jawbone and three small bones in its inner ear. The platypus belongs to a small sub-group, or order, of mammals called monotremes; all four other monotremes are species of the spiny anteater, or echidna. Monotremes are the oldest surviving order of mammals. While other mammals, including marsupials like kangaroos and placental mammals like humans, give birth to live young, monotremes lay eggs, like birds and reptiles. Their name comes from the Greek for “single opening,” because monotremes have one body opening called a cloaca that's used for reproduction, urination, and defecation. Other mammals have a separate opening for at least one of these functions, if not all three, while most birds, reptiles, and amphibians have a similar all-purpose cloaca.

The platypus is also one of only a few venomous mammals; its hind legs have sharp poisonous spurs on them. In short, the platypus wears its evolutionary history on its sleeve: it's a mammal in all the most important ways, but it shares more characteristics with birds and reptiles than other mammals do. What's more, some of its mammalian traits are less sophisticated than those of marsupials and placental mammals. That's because the monotremes split off from our common mammalian ancestor much earlier than other groups did. Understanding the platypus genome could help scientists fill in the genetic timeline that led to modern humans. So far, the researchers have compared the platypus genome to that of the human, mouse, dog, opossum, and chicken, looking for particular genes that are linked to both mammalian and non-mammalian traits. They're also looking more closely at the genes to understand how they differ from those of other mammals, and why they produce more primitive mammalian traits: for example, although monotremes make milk for their young, they have no nipples. Instead, the milk simply leaks onto the mother's belly, and the babies lick it off.

Breaking down mammalian traits like milk production into evolutionary steps may ultimately help scientists understand how all mammals, including people, function. Now try and answer these questions: What are monotremes? What makes them mammals? How are they different from other mammals? Why might the platypus share more genes with reptiles and birds than other mammals do? Why is the platypus an important animal to understand genetically? Why sequence the genomes of animals at all? You may want to check out the May 31, 2008, Science Update Podcast to hear further information about this Science Update and the other programs for that week. This podcast's topics include: how Rhesus monkey social relationships reveal a link between stress and overeating, what the platypus genome can tell us about being a mammal, how an antidepressant restores vision in rats, negligent mother mice that have abnormal brain chemistry, and fruit flies uncovering secrets of aging and pain. Untitled Document Taxonomy Together with the four species of echidna, the platypus is one of five species of monotremes, the only mammals that lay eggs instead of giving birth to live young.

It is the sole living species of the family, Ornithorhynchidae, and genus Ornithorhynchus, though a number of related species have been found in the fossil record. The common name, platypus, is Latin derived from the Greek words p?at?? ("platys", flat, broad) and p??? ("pous", foot), meaning "flat foot". Early British settlers called it by many names, such as watermole, duckbill, and duckmole. Some of the names traditionally used by Australian aborigines for the platypus are mallangong, tambreet and boonaburra. The name platypus is often prefixed with the adjective "duck-billed" to form duck-billed platypus, even though there is only one species of platypus. George Shaw assigned it as a Linnaean genus name when he initially described it, but the term was quickly discovered to already belong to the wood-boring ambrosia beetle (genus Platypus). It was independently described as Ornithorhynchus paradoxus by Johann Blumenbach in 1800.

Following the rules of priority of nomenclature, it was officially renamed as Ornithorhynchus anatinus. The scientific name Ornithorhynchus is derived from ???????????? ("ornithorhynkhos"), which literally means "bird snout" in Greek, and anatinus which means "duck-like" in Latin. There is no universally agreed upon plural of "platypus" in the English language. Scientists generally use "platypuses", "platypoda", or simply "platypus". Conversationally, "platypi" is also used for the plural, although this is pseudo-Latin. Description The platypus (Ornithorhynchus anatinus), is a unique Australian animal. Its webbed feet and large, rubbery snout are features that appear closer to those of a duck than to those of any known mammal. Even the skeleton of the platypus is drastically different than most mammals. The platypus has extra bones in the shoulder girdle, including an interclavicle, which is not found in other mammals. Its gait resembles that of a reptile, with legs that are on the sides of the body, rather than underneath.

Platypuses are readily identified by their streamlined body, low body profile, webbed feet, broad tail, and characteristic muzzle or bill. They have a smooth swimming action and have the absence of visible ears, distinguishing them from other Australian mammals. The foot webbing is more pronounced on the front feet and is folded back when walking on land. The platypus uses its tail for its swimming motion and storage of fat reserves which will be used in the winter months. The 2 inch wide snout is soft, pliable, and hairless. Unlike a bird's beak (in which both the upper and lower parts of the beak separate to reveal its mouth), the snout of the platypus is a sensory organ with the mouth on the underside. The snout is also extremely sensitive to touch which is highly useful since the platypus closes its eyes and ears underwater. The nostrils are located on the dorsal surface of the snout while the eyes and ears are located in a groove set just back from it; this groove is closed when swimming. internt.nhm.ac.uk The body and the broad, flat tail of the platypus are covered with dense brown fur that traps a layer of insulating air to keep the animal warm.

The fur is composed of two layers, which an outer coat that does not allow water to penetrate to the inner layer. The fur on the broad flat tail is coarse and bristly. Its usual coloration is deep brown on the back and sides of the head, body and upper surfaces of the limbs. The underside is a golden color although silky grey is not uncommon. Weight varies considerably from 1.5 lb to 5.3 lb with males typically being larger than females: males average 20 in total length while females average 17 in. There is substantial variation in average size from one region to another, and this pattern does not seem to follow any particular climatic rule and may be due to other environmental factors such as predation and human encroachment. Platypuses in Tasmania tend to be larger than those found in the mainland of Australia, possibly because of the lack of introduced predators. The failure to establish the red fox in particular is theorized to be a contributing factor to both the greater average size and abundance of the platypus in the state. purgatorio1.com Platypus young have three-cusped molars which they lose before or just after leaving the breeding burrow. Adults have no teeth.

Once the molars fall out, heavily keratinised pads come in their place. As is true of all mammals, the tiny bones that conduct sound in the middle ear are fully incorporated into the skull, rather than lying in the jaw as the pre-mammalian ancestors. However, the external opening of the ear still lies at the base of the jaw, much like the pre-mammalian animals. The monotremes have lower body temperatures than other mammals. The species is still endothermic, maintaining its low body temperature, even while foraging for hours in water below 40°F. The platypus has an average body temperature of 88–90°F rather than the 100°F typical of placental mammals. Research suggests this is due to gradual adaptation to harsh environmental conditions on the part of the small number of surviving monotreme species rather than a historical characteristic of monotremes. In captivity, platypuses have survived to seventeen years old and wild specimens have been recaptured at eleven years old. Mortality rates for adults in the wild appear to be low.

Natural predators include snakes, water rats, goannas, hawks, owls and eagles, and low platypus numbers in the northern Australia are possibly due to predation by crocodiles. The introduction of red foxes as a predator for rabbits may have had some impact on its numbers on the mainland. Distribution and habitat The platypus is widespread in eastern Australia, ranging from tropical lowlands to sub-alpine areas. In Tasmania the platypus is common in the lakes of the Central Highlands (even in lakes over 914 m above sea level), and in rivers and streams of the south, southwest and northwest coasts. Although platypuses are strong swimmers, they are not fast and prefer slow flowing streams. However, closer settlement is reducing the numbers in certain coastal rivers. Platypuses live in burrows that they dig on the banks of fresh water rivers, lakes or streams. These straight burrows are usually 4.5 to 9 m in length, oval shaped in cross section and are constructed just above the water line, often obscured by vegetation. Their territorial range may be up to 4.5 miles, with a male's home range overlapping with that of 3 or 4 females.

Platypuses have been heard to emit a low growl when disturbed and a range of other vocalisations have been reported in captive specimens. rainforest-australia.com Electrolocation Monotremes are the only mammals known to have a sense of electroreception, meaning they locate their prey in part by detecting electric fields generated by muscular contractions. The platypus' electroreception is the most sensitive of any of the monotremes. The electroreceptors are located in rostro-caudal rows in the skin of the bill, while mechanoreceptors, which detect physical touch, are uniformly distributed across the bill. The platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors. This would explain the animal's characteristic side-to-side head motion when hunting. The simultaneous electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, would also allow for detection of the prey’s location. The electroreceptors could be used to distinguish animate and inanimate objects when digging in the bottom of streams with its bill (in which the mechanoreceptors would be continuously stimulated).

When disturbed, its prey would generate tiny electrical currents in their muscular contractions which the sensitive electroreceptors of the platypus could detect. Experiments have shown that the platypus will even react to artificial objects if a small electrical current is passed through it. Diet When foraging on the bottom, platypus swim with their eyes, ears and nostrils closed, using their electro-sensitive bill to locate and probe for food. The platypus is a carnivore. They capture a range of prey including annelid worms and insect larvae, freshwater shrimps, and freshwater crayfish that it digs out of the riverbed with its snout or catches while swimming. Behavior The platypus is generally regarded as nocturnal and crepuscular, but individuals are also active during the day, particularly when the sky is overcast. Platypuses are solitary animals that only come together to mate, however, several individuals may be found living in close proximity. They are shy and wary, usually venturing out only in the early morning and evening, although there is considerable variability in the time that individuals are active. Grooming of the fur is very important and is carried out in the water or on land.

In some areas platypus spend a surprising amount of time out of water, crossing land between tarns or dams and even foraging for worms in waterlogged paddocks. Platypus forage for food for about 12-13 hours every day and can consume up to half their own body weight a day, but needs to eat about 20% of its own weight each day. It utilizes cheek-pouches to carry prey to the surface where they are eaten. They dive for between 20-40 seconds during foraging, but few exceed the estimated aerobic limit of 40 seconds. They recover at the surface for only 10 seconds between dives and can perform about 80 dives per hour. Uniquely among mammals, it propels itself when swimming by alternate rowing motion with the front two feet. Although all four feet of the platypus are webbed, the hind feet (which are held against the body) do not assist in propulsion, but are used for steering in combination with the tail. An interesting behavior that has been observed in platypus is "wedging". The animal wedges itself beneath a rock or tree stump while underwater.

It is possible that the animal is resting, as its metabolic rate while wedging is less than that of resting at the surface thereby reducing its need to breathe. Conservation status The International Union for the Conservation of Nature and Natural Resources lists the platypus on its Red List as Least Concern. The platypus is protected throughout Australia. Except for its loss from the state of South Australia, the platypus occupies the same general distribution as it did prior to European settlement of Australia. It is quite common and does not appear to be in immediate danger of extinction thanks to conservation measures, but it could be impacted by disruption caused by dams, irrigation, pollution, and the illegal netting and trapping of fish. Its current and historical abundance, however, is less well known and it has probably declined in numbers, although still being considered as common over most of its current range. The species was extensively hunted for its fur until the early years of the 20th century and, although protected throughout Australia in 1905, up until about 1950 it was still at risk of drowning in the nets of inland fisheries. There is also concern about the potential impact in Tasmania because of an infection caused by a fungus, Mucor amphiborum.

Affected animals develop ulcers on various parts of the body that can lead to death from secondary infection and an inability to control body temperature. The same fungus so far causes no problems to the platypus on the Australian mainland. The Tasmania Parks and Wildlife Service and Biodiversity Conservation Branch Department of Primary Industries and Water are collaborating to monitor the effects of the infection on the platypus population in Tasmania. Venom The platypus is one of eight venomous mammalian species. Venom is produced in glands in the legs of the male. Female platypuses, in common with echidnas, have rudimentary spur buds which do not develop (dropping off before the end of their first year) and lack functional venom producing glands. The glands are kidney-shaped and alveolar and are connected by a thin-walled duct to each spur on the inner side of the hind limb. The spur is used to inflict wounds on natural enemies and other males, and may possibly play some part in mating. The poison is capable of inflicting a very painful injury to humans. Since only males produce venom and production rises during the breeding season it is theorized that it is used as an offensive weapon to assert dominance during this period.

The venom, composed largely of defensin-like proteins (DLPs), is unique to the platypus. Edema quickly develops around the wound and gradually spreads throughout the affected limb. Information obtained from case histories and anecdotal evidence indicates that the pain develops into a long-lasting extreme sensitivity to pain that persists for days or even months. The venom appears to have a different function from those produced by non-mammalian species: its effects are non-life threatening but nevertheless powerful enough to seriously impair the victim. Evolution and History The extinct monotremes (Teinolophos and Steropodon) were closely related to the modern platypus. A fossilized Steropodon was discovered in New South Wales, whose lower jawbone had three molar teeth, however the adult contemporary platypus is toothless. The molar teeth were initially thought to be three-cusped shape which would have supported the initial theory that monotremes evolved after placental mammals, but later research has suggested while they have three cusps they evolved under a separate process.

The oldest discovered fossil is thought to be about 110 million years old, which means that the platypus-like animal was alive during the Cretaceous period, making it the oldest mammal fossil found in Australia. Monotrematum sudamericanum, another fossil relative of the platypus has been found in Argentina, indicating that monotremes were present in the supercontinent of Gondwana when the continents of South America and Australia were joined via Antarctica (up to about 167 million years ago). When the platypus was first discovered by Europeans in the late 1700s, a pelt and sketch were sent back to the United Kingdom by Captain John Hunter. The British scientists were at first convinced that the odd collection of physical characteristics must have been a hoax. George Shaw, who produced the first description of the animal in the Naturalist's Miscellany in 1799, stated that it was impossible not to have doubts about this animal. Robert Knox believed it may have been produced by some Asian taxidermist. It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal.

Shaw even took a pair of scissors to the skin to check for stitches. The platypus and other monotremes were very poorly understood for many years and some of the 19th century myths that grew up around them, for example, that the monotremes were "inferior" or quasi-reptilian, still endure. It is now generally accepted that modern monotremes are the survivors of an early branching of the mammal tree; later branches giving rise to the marsupial and placental groups. Although in 1947, William King Gregory had theorized that placental mammals and marsupials may have diverged earlier with a subsequent branching dividing the monotremes and marsupials, but later research and fossil discoveries have suggested this is incorrect. Much of the world was introduced to the platypus in 1939 when National Geographic magazine published an article on the platypus and the efforts to study and raise it in captivity. This is a difficult task, and only a few young have been successfully raised since — notably at Healesville Sanctuary in Victoria, located in the south-eastern corner of Australia.

The leading figure in these efforts was David Fleay who established a platypussary, a simulated stream in a tank, at the Healesville Sanctuary and had a successful breeding in 1943. In 1972, he found a dead baby of about 50 days old, which had presumably been born in captivity, at his wildlife park at Burleigh Heads on the Gold Coast, Queensland. Healesville repeated its success in 1998 and again in 2000 with a similar stream tank. Taronga Zoo in Sydney bred twins in 2003, and had another birth in 2006. Because of the early divergence from marsupials and placental mammals and the low numbers of extant monotreme species, it is a frequent subject of research in evolutionary biology. In 2004, researchers at the Australian National University discovered the platypus has ten sex chromosomes, compared to two (XY) found in most other mammals (for instance, a male platypus is always XYXYXYXYXY). Furthermore, one of the platypus’s Y chromosomes shares genes with the ZZ/ZW sex chromosomes found in birds.

This news further pronounced the individuality of the platypus in the animal kingdom. Introduction to the Monotremata Echidna. Photo by Dr. Lloyd Glenn Ingles © 2001 California Academy of Sciences. There are only five living monotreme species: the duck-billed platypus and four species of echidna (also known as spiny anteaters). All of them are found only in Australia and New Guinea. Monotremes are not a very diverse group today, and there has not been much fossil information known until rather recently. In some ways, monotremes are very primitive for mammals because, like reptiles and birds , they lay eggs rather than having live birth. In a number of other respects, monotremes are rather derived, having highly modified snouts or beaks, and modern adult monotremes have no teeth. Like other mammals , however, monotremes have a single bone in their lower jaw, three middle ear bones, high metabolic rates, hair, and they produce milk to nourish the young.

Click on the buttons below to learn more about Monotremes Read about monotremes at the University of Tasmania, who have one of the best sites on the web about living monotremes. Try the University of Michigan's Animal Diversity Web for more information about living monotremes. The Tasmanian Mammals page includes distributional information on monotremes. Platypus and echidnas are the only two mammals that lay eggs Platypus and echidnas are the only two mammals that lay eggs Posted in: #animals , #platypus , #echidnas , #mammals , #eggs , #monotremes 2012/01/03 Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). The only surviving examples of monotremes are all indigenous to Australia and New Guinea, although there is evidence that they were once more widespread. Among living mammals they include the platypus and four species of echidnas (or spiny anteaters).

Like other mammals, monotremes are warm-blooded with a high metabolic rate (though not as high as other mammals), have hair on their bodies, produce milk through mammary glands to feed their young, have a single bone in their lower jaw and have three middle-ear bones. Monotremes were very poorly understood for many years, and to this day, some of the 19th century myths that grew up around them endure. It is still sometimes thought, for example, that the monotremes are "inferior" or quasi-reptilian, and that they are a distant ancestor of the "superior" placental mammals. It now seems clear that modern monotremes are the survivors of an early branching of the mammal tree; a later branching is thought to have led to the marsupial and placental groups. Monotremes lay eggs. However, the egg is retained for some time within the mother, who actively provides the egg with nutrients. Monotremes also lactate, but have no defined nipples, excreting the milk from their mammary glands via openings in their skin. All species are long-lived, with low rates of reproduction and relatively prolonged parental care of infants.

Monotremes A biography of the Australian continent Monotremes A 100 million year old monotreme, an early platypus, Steropodon galmani, is the earliest mammal found in Australia. The fossil is an opalised jaw of Cretaceous age from Lightning Ridge , New South Wales. It is from the Lower Cretaceous (Albian) Griman Creek Formation . Being about the size of a house cat it is one of the largest known Mesozoic mammals, in size it overlapped with some of the smaller dinosaurs. The well-developed teeth of this animal already display the characteristic shape of monotremes. The only living monotremes are the platypus and 2 species of echidna . The term monotreme refers to ï¿½oneï¿½ ï¿½holeï¿½, being the cloaca, and this is indeed one of two defining features of this group. The cloaca is a common point of exit for all urinary, defecatory and reproductive systems. All monotremes reproduce by laying eggs, and nourishing their young with milk which is secreted through mammary glands located in their skin.

The 2 types of monotreme are the platypus and the echidna. Extant species are only found in Australia and New Guinea although fossil teeth from an extinct Platypus species has also been found in Argentina, revealing that they were once distributed over Southern Gondwana . The monotremes have a distinct gait, reminiscent of the reptilian species, due to the positioning of the legs on the side of the body as opposed to underneath it. All individuals have a 15 mm spur above the heel of each hind leg, which whilst appearing vestigial in the echidna, houses a potent toxin (produced by the crural gland in the thigh), in male platypuses. It is the only Australian mammal known to be venomous. The males will use these spurs as weapons if they feel threatened, and inject poison into their foe. Venom production peaks with the breeding season, suggesting a use in sexual competition. Fossil record: The early mammalian tree split into 3 main groups (monotremes, placentals and marsupials). It is now thought that the first group to split off were the Monotremes.

However, they have left us scant information in the fossil record, and what little evidence there is suggests that this group diverged in the Early Cretaceous period. After this point, it would appear that the Monotremes underwent evolution (molecular and morphological) at a much slower pace than is known for the therian mammals. The earliest fossil find for this group were from the Lightning Ridge Opal Fields of NSW, and consisted of the lower jaw bone of a 100 million years ago species, Steropodon galmani ï¿½ one of the first mammalian species known from the Mesozoic Era. These finds, and other like it, indicate that Monotremes first evolved in Australia (during Late Jurassic or early Cretaceous ), prior to spreading to South America and Antarctica. Both of these land masses were at this point, obviously connected to Australia. A jawbone of a primitive platypus, Teinolophos trusleri , that had already evolved the flat beak and aquatic lifestyle, has been found at Flat Rocks , Victoria,.

It has been dated to the Aptian part of the Lower Cretaceous , about 123Ma, a time when it was believed the early mammals were unspecialised insectivores that survived by staying insignificant, keeping out of the way of the ruling dinosaurs. Maybe it could evolve on the then Australian Peninsula of Gondwana, where for some reason that is still debated, dinosaurs were late arriving, and possibly in lower numbers than elsewhere in Gondwana. See the Peninsula Effect . A fossil platypus from the Early Miocene , Obdurodon dicksoni , has been found in the Riversleigh Fossil Site , northwest Queensland. Another species, Obdurodon insignis, from the Oligocene deposit at Lake Palankarinna , and also from an Oligocene deposit in the Lake Frome Embayment. Unlike the vestigial teeth of the modern platypus, the Obdurodon species had well developed teeth of a distinctive shape. Apart from these teeth, the central Australian deposits have only produced isolated teeth, a fragment of a lower jaw and a part of a pelvis. The Australian fossil record also includes some specimens of Giant Echidnas from the Pleistocene era.

These were as large as sheep, and have been found in Western Australia (in Mammoth Cave ), and constitute the largest monotremes ever discovered. (Zaglossus hacketti). The extant platypus is the only surviving descendant of Obdurodon. It had specialised its dentition to the point where its teeth have almost disappeared completely, as well reduced its size, and simplified most of its cranial anatomy. It is a sad fact of evolution that when an animal specialises in a particular direction, as the platypus has, it tends to be found to be in decline. The present populations of the platypus seems to be sufficient to believe it is not heading for extinction, but the habitat is has specialised to live in, permanent river systems, would no doubt be safe if humans were not present on the continent, but not when the rivers are being affected by deforestation in both rainforests and open forests, and the addition of all sorts of pollution, such as fertilisers and pesticides, and other chemicals used by the people living along the rivers it inhabits. One result of deforestation is the increase in the destructiveness of floods that can destroy the burrow systems of the platypus.

Any surviving platypuses might dig a new burrow system, but in the mean time they would be exposed to predation. Letters to Nature Nature 377, 418 - 420 (05 October 2002); doi:10.1038/377418a0 Monotremes - Monotremata - The Animal Encyclopedia Share By Laura Klappenbach Monotremes (Monotremata) are a unique group of mammals that lay eggs instead of giving birth to live young like other mammals (such as placental mammals and marsupials ). Monotremes include several species of echidnas and the platypus. Monotremes differ from other mammals in that they have a singoe opening for their urinary, digestive and reproductive tracts (this single opening is known as a cloaca and is similar to the anatomy of reptiles). Monotremes lay eggs and like other mammals lactate (produce milk) but instead of having nipples like other mammals, monotremes secrete milk through mammary gland openings in the skin. Adult monotremes do not have any teeth. Monotremes are long-lived mammals.

They exhibit a low rate of reproduction. Parents take close care for young and tend to them for long periods of time before they become independent. The fact that monotremes lay eggs is not the only factor that distinguishes them from other mammal groups. continue reading below our video 10 Best Universities in the United States Monotremes also have unique teeth that are thought to have developed independently of the teeth that placental mammals and marsupials have (even though the teeth may be convergent evolutionary adaptations due to similarities). Monotremes also have an extra set of bones in their shoulder (the intercalvical and coracoid) which are missing from other mammals. Monotremes also differ from other mammals in that they lack a structure in their brain called the corpus callosum (the corpus callosum forms a connection between the left and right hemispheres of the brain). Monotremes are the only mammals known to possess electroreception, a sense that enables them to locate prey by the electric fields generated by its muscle contraction. Of all monotremes, the platypus has the most sensitive level of electroreception. Sensitive electroreceptors are located in the skin of the platypuses bill.

Using these electroreceptors, the platypus can detect the direction of the source and the strength of the signal. Platypuses swing their head from side to side when hunting in water as a way of scanning for prey. Thus when feeding, platypuses do not use their sense of sight, smell or hearing and rely instead only on their electroreception. Evolution: The fossil record for monotremes is rather sparse but it is thought that monotremes diverged from other mammals early on, before marsupials and placental mammals evolved. A few monotreme fossils from the Miocene are known. Fossil monotremes from the Mesozoic include Teinolophos, Kollikodon, and Steropodon. Classification: Monotremes are mammals. There are two groups of monotremes, the platypus and the echidnas. The platypus is the only member of its family. There are four living species of echidnas, the short-beaked echidna, the Sir David's long-beaked echidna, the eastern long-beaked echidna, and the western long-beaked echidna.

The platypus (Ornithorhynchus anatinus) is an odd looking mammal with a broad bill (that resembles the bill of a duck), a tail (that resembles the tail of a beaver) and webbed feet. Another oddity of the platypus is that male platypuses are venomous. A spur on their hind limb delivers a mixture of venoms that are unique to the platypus. Echidnas include four living species. They feed on ants and termites and are solitary animals. They are covered with spines and course hair. Although echidnas resemble hedgehogs, porcupines and anteaters, they are not closely related to any of these other mammal groups. Echidnas have short limbs that are strong and well-clawed, making them good diggers. They have a small mouth and do not have any teeth. They feed by ripping apart rotten logs, ant nests and mounds then licking up ants and insects with their sticky tongue. Echidnas are named after a monster of the same name, from Greek mythology.

Monotremes Monotremes Sarcopterygii; Tetrapoda; Amniota; Synapsida ; Prototheria; Monotremata Click thumbnails for larger images Short-beaked echidna taxidermy Short-beaked echidna skeleton Platypus taxidermy The order Monotremata is the only extant group within the subclass Prototheria - the oldest living taxon of theclass Mammalia. Whilst there has never been much doubt that monotremes split off from other mammal group at an early stage, due to their many ancestral reptilian characters (see below), the mid 20th-Century saw much dispute regarding the evolutionary positioning of the other two major groups of mammal - the metatherians (marsupials) and the eutherians (placental mammals) - with respect to the monotremes. The question was whether the metatherians were the sister clade of the monotremes or of the eutherians. This proved a difficult question to answer, as much of our understanding of mammalian phylogeny has been gained through comparisons of tooth morphology, yet monotremes are toothless - a character that is certainly not ancestral.

However, much study on the ancestral amniote features of monotremes, as well as a recent complete analysis of their genome, has shown that they split off from other mammal groups around 200 million years ago, at the Triassic-Jurassic boundary. Therefore, Metatheria and Eutheria together form the clade Theria (live-bearing mammals), to the exclusion of Prototheria. The cladogram below summarises these relationships: Diversity and Lower Taxonomy: The monotremes are a group of highly specialised egg-laying predatory mammals, containing the platypus and echidnas. There are only five living species of monotreme, contained within two families: Family Ornithorhynchidae: the platypus, a single species in a single genus, Ornithorhynchus anatinus. Family Tachyglossidae: the echidnas. Four species divided into two genera: 1. Tachyglossus: one species of short-beaked echidna (Tachyglossus aculeatus). 2. Zaglossus: three species of long-beaked echidnas.

(One of these, Zaglossus attenboroughi, a species from the Papua province of the island of New Guinea named after British naturalist Sir David Attenborough, has never been seen in the wild and is only known to science through a single museum specimen from 1961! In 2007, researchers at the Zoological Society of London confirmed that Sir David's echidna is not extinct, by finding burrows and tracks made by the species) Distribution and Habitat: Endemic to Australasia - an important point to note as it means that they represent a whole subclass of extant mammalian life in a single geographic region. While the platypus is semi-aquatic, the echidnas are all terrestrial, and their respective distributions and habitats are as follows: Platypus - Confined to Eastern Australia and Tasmania Conservation Status (IUCN): Platypus - Least Concern (LC) - However, although the platypus is common, it has a fairly narrow, specific habitat range and, consequently, is distributed in localised regions. It is therefore vulnerable to local extinction.

Short-beaked echidna - Least Concern (LC) Long-beaked echidna - Critically Endangered (CR) Features: Males have a spur on their ankles, which bears poison in the platypus. Toothless - platypuses have a leathery electrosensory bill, with crushing horny plates to break through the tough exoskeleton of arthropods; echidnas have an elongate horny rostrum with a long sticky tongue for collecting insects. A range of mammalian characters: Produce milk (lactate) from mammary glands. However, while therians have nipples, monotremes do not, and consequently the young suck milk from patches of mammary hairs - specialised areas of fur positioned around the ventral openings of the mother's mammary glands. Epipubic bones - two thin rod-like bones extending anteriorly from the pubic bones of the pelvic girdle. Lower jaw (mandible) made up of a single bone, the tooth-bearing dentary . A middle ear formed of three bones: the incus, malleus, and stapes.

While the stapes is present in the middle ear of all living tetrapods, the incus and malleus are modified bones from the typical amniote jaw joint. The jaws of non-mammalian amniotes articulate via the quadrate of the upper jaw, and the articular of the lower jaw; in mammals, the quadrate migrated to form the incus, while the articular became the malleus, leaving a jaw joint formed of the dentary articulating with the squamosal (the angular bone of the non-mammalian amniote lower jaw is used as a bony support for the eardrum in mammals). The following diagram illustrates these differences: A range of ancestral reptilian characters: Egg-laying (oviparity); however, these soft-shelled eggs are short-lived, the young hatching after around ten days and being dependent on mother's milk for up to six months after. Sprawling gait (although it is possible that this is a derived feature of monotremes, relating to specialisations for swimming in the platypus, and for digging in the echidnas).

A single common opening for the digestive, urinary, and reproductive tract, called the cloaca (the general amniote condition). In therian mammals (marsupials and placentals), there are two openings: one for the digestive system, and one for the urogenital tract. Presence of the coracoid - the ventral bone of the shoulder girdle seen in all non-mammalian amniotes. This is the general amniote condition, where the humerus articulates with the shoulder girdle at the junction between the coracoid and the scapula (commonly termed the shoulder blade). Not entirely homeothermic. While monotremes are - meaning that they regulate their body temperature using heat produced during endothermic metabolism - they are fairly poor at maintaining a constant body temperature during extreme enviromental conditions. Monotreme - Video Learning - WizScience.com - YouTube Monotreme - Video Learning - WizScience.com Want to watch this again later? Sign in to add this video to a playlist. Need to report the video? Sign in to report inappropriate content. The interactive transcript could not be loaded. Loading... Rating is available when the video has been rented. This feature is not available right now.

Please try again later. Published on Sep 1, 2015 "Monotremes" are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals . The only surviving examples of monotremes are all indigenous to Australia and New Guinea, although there is evidence that they were once more widespread. The existing monotreme species are the platypus and four species of echidnas . There is currently some debate regarding monotreme taxonomy. The word "monotreme" comes from the Greek μονός, "monos" and τρῆμα, "trema" , referring to the cloaca. Like other mammals, monotremes are warm-blooded with a high metabolic rate ; have hair on their bodies; produce milk through mammary glands to feed their young; have a single bone in their lower jaw; and have three middle-ear bones. In common with reptiles and marsupials, monotremes lack the connective structure which in placental mammals is the primary communication route between the right and left brain hemispheres.

The anterior commissure does provide an alternate communication route between the two hemispheres, though, and in monotremes and marsupials it carries all the commissural fibers arising from the neocortex, whereas in placental mammals the anterior commissure carries only some of these fibers. Extant monotremes lack teeth as adults. Fossil forms and modern platypus young have a "tribosphenic" form of molars , which is one of the hallmarks of extant mammals. Some recent work suggests that monotremes acquired this form of molar independently of placental mammals and marsupials, although this is not well established. Monotreme jaws are constructed somewhat differently from those of other mammals, and the jaw opening muscle is different. As in all true mammals, the tiny bones that conduct sound to the inner ear are fully incorporated into the skull, rather than lying in the jaw as in cynodonts and other premammalian synapsids; this feature, too, is now claimed to have evolved independently in monotremes and therians, although, as with the analogous evolution of the tribosphenic molar, this is disputed. The external opening of the ear still lies at the base of the jaw.

The sequencing of the platypus genome has also provided insight into the evolution of a number of monotreme traits, such as venom and electroreception, as well as showing some new unique features, such as the fact that monotremes possess 10 sex chromosomes and that their X chromosome resembles the sex chromosome of birds, suggesting that the two sex chromosomes of marsupial and placental mammals evolved more recently than the split from the monotreme lineage. This feature, along with some other genetic similarities with birds, such as shared genes related to egg-laying, is thought to provide some insight into the most recent common ancestor of the synapsid lineage leading to mammals and the sauropsid lineage leading to birds and modern reptiles, which are believed to have split about 315 million years ago during the Carboniferous. The presence of vitellogenin genes is shared with birds, suggesting that when the common ancestor of mammals from ~225 million years ago split into monotremes, marsupials, and placental mammals, egg laying was retained in monotremes and lost in all other mammals.

DNA suggests that while this trait is shared and is synapomorphic with birds, platypuses are still mammals and they evolved lactation with other mammals. L-ascorbic acid is synthesized only in the kidneys. Wiz Science™ is "the" learning channel for children and all ages. SUBSCRIBE TODAY Disclaimer: This video is for your information only. The author or publisher does not guarantee the accuracy of the content presented in this video. USE AT YOUR OWN RISK. Background Music: "The Place Inside" by Silent Partner (royalty-free) from YouTube Audio Library. This video uses material/images from , which is released under Creative Commons Attribution-Share-Alike License 3.0 . This video is licensed under Creative Commons Attribution-Share-Alike License 3.0 . To reuse/adapt the content in your own work, you must comply with the license terms. Category

Question: The platypus and four species of which mammal are the only surviving monotremes?
Answer: ECHIDNA